patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/testdir/test_winbar.vim b/src/testdir/test_winbar.vim
index b946bcd..954c3e0 100644
--- a/src/testdir/test_winbar.vim
+++ b/src/testdir/test_winbar.vim
@@ -132,8 +132,8 @@
       wincmd j
       wincmd _
   END
-  call writefile(lines, 'XtestWinbarNotVisble', 'D')
-  let buf = RunVimInTerminal('-S XtestWinbarNotVisble', #{rows: 10})
+  call writefile(lines, 'XtestWinbarNotVisible', 'D')
+  let buf = RunVimInTerminal('-S XtestWinbarNotVisible', #{rows: 10})
   call VerifyScreenDump(buf, 'Test_winbar_not_visible', {})
 
   " clean up
@@ -151,8 +151,8 @@
       wincmd j
       wincmd _
   END
-  call writefile(lines, 'XtestWinbarNotVisble', 'D')
-  let buf = RunVimInTerminal('-S XtestWinbarNotVisble', #{rows: 10})
+  call writefile(lines, 'XtestWinbarNotVisible', 'D')
+  let buf = RunVimInTerminal('-S XtestWinbarNotVisible', #{rows: 10})
   call VerifyScreenDump(buf, 'Test_winbar_not_visible_custom_statusline', {})
 
   " clean up